Hutchison's U.K. operator Three is trying to buy Telefonica's 02, a purchase that would create Britain's biggest wireless operator and remove one of its four big mobile carriers -- hence White's fears about higher phone bills for locals.

Three, an operator in six European countries, overcame similar antagonism from local regulators when buying rivals in Austria and Ireland. The final decision-making power rested in Brussels because of the pan-European nature of the companies involved. European competition watchdogs were won over by concessions such as renting capacity to other players.

This time around the script is unfolding in a similar, if noisier, manner. White penned a Financial Times op-ed on Monday arguing that consumers and businesses could face price hikes while network investment might fall.

But, as in the cases of Austria and Ireland, it will not be her decision to make, nor that of British competition regulator the CMA. Since Hutchison and Telefonica both earn much of their revenue outside the U.K., the EU's competition watchdog Margrethe Vestager is in charge. She's expected to unveil her list of complaints to Hutchison as early as this week.

Only then will Hutchison begin discussions with Brussels about what it needs to offer competitors to get a deal approved. The combination would have about 37 percent of total mobile market service revenue in the U.K., compared with 35 percent for BT's EE and 28 percent for Vodafone, according to Haitong Research. Hutchison will argue that Three will struggle without a deal because it doesn't have enough spectrum to compete, harming its ability to add customers.

Britain's Mobile Market

Share by number of customers

Bloomberg Intelligence data; as of end 2014

In Li's favor is the fact that Rupert Murdoch's Sky, the country's pay-TV leader, favors the deal because it would like Hutchison to offer remedies that let it build its own mobile business. Another low-cost broadband provider Talk Talk is also maneuvering to take advantage of the remedies, while John Malone's Virgin Media could be interested, as might Xavier Niel's Iliad.

One thing's clear, though: compared with her predecessor Joaquin Almunia who waved through three mobile deals during his tenure, Vestager's more skeptical. She already scuppered a deal in Denmark, and has said benefits from telecoms consolidation tend to flow to shareholders not consumers.

Telecoms on a Tear

Sector shares have performed better than other European sectors

Bloomberg

Indeed, European telecoms stocks seem to be pricing in optimism about sector rationalization, trading at an average price to forward earnings multiple of about 23 times, according to Bloomberg data, ahead of other sectors.

Yet winning Vestager over won't be easy. Hutchison may be able to swing it by offering structural remedies, such as selling spectrum and capacity to Sky or Talk Talk. But it needs to weigh how far to take concessions before the economic rationale behind the deal no longer makes sense.

And it's not just Hutchison's U.K. deal in the balance. Vestager will also review its proposed tie-up of 3 Italia with Vimpelcom's Wind. So while Britain's intervention won't be decisive, the broader battle is far from won. With Vestager the arbiter, the flow of European telco earnings remains in the gift of the regulators.

This column does not necessarily reflect the opinion of Bloomberg LP and its owners.